What aircraft was involved and where did it happen?

The accident on null involved a 22-06-2008, at D-EFXY, BE.

What was the probable cause of the accident?

The engine failure was caused by fuel starvation resulting from the pilot's use of the right-hand fuel tank, compounded by a misunderstanding of the specific fuel system limitations and inadequate cockpit markings.

Engine Failure and Hangar Crash Involving Piper PA-18-150

A Piper PA-18-150 experienced an engine failure during a glider tow, resulting in a total loss of the aircraft and a collision with a hangar.

What happened

On June 22, 2008, a Piper PA-18-150, registration D-EFXY, was performing aerotow operations for a glider club near Kiewit. During its eleventh flight of the day, while towing a Grob Twin Astir glider, the engine ceased functioning at an altitude of approximately 300 feet.

Facing immediate obstacles including trees and residential buildings, and lacking sufficient altitude to return to the airfield, the pilot attempted an emergency landing on the roof of nearby hangars. During the maneuver, the pilot signaled the glider to release the tow rope; however, the glider pilot did not initially recognize the signal. After the rope was eventually released, the towing aircraft struck a tree before impacting the sidewall of a hangar, destroying the aircraft. The pilot escaped the wreckage with only minor injuries.

The investigation

The AAIU(Be) investigation focused on the engine failure and the fuel system configuration of the aircraft. The aircraft had been modified with a more powerful 180 HP engine, which necessitated significant changes to the fuel system, including new fuel lines, vented caps, and a different carburetor air box.

Investigators examined the fuel selector valve and cockpit gauges, finding that the markings did not fully comply with the required Supplemental Type Certificate (STC). Specifically, the fuel selector valve lacked clear indicators for Main or Auxiliary tank settings, and the left-hand fuel gauge did not accurately reflect the reduced usable fuel capacity mandated by the flight manual.

Findings

The engine failure was caused by fuel starvation.
The pilot had selected the right-hand fuel tank for the flight and did not switch to the left-hand tank.
The right-hand header tank was found to be empty at the time of the crash.
The aircraft's high fuel consumption rate, driven by the 180 HP engine and a four-blade propeller, contributed to the rapid depletion of fuel.
The pilot was operating under a high-intensity schedule, with very short turnaround times between flights, which pressured the need to maximize on-board fuel usage.
There was a misunderstanding of the specific operational limitations regarding fuel tank usage as defined in the Aircraft Flight Manual.
Cockpit instrumentation and selector valve markings were imprecise or non-compliant with the STC, leading to confusion regarding usable fuel quantities.

Safety action

The Belgian Civil Aviation Authority (BCAA) was directed to ensure that all STC modifications are correctly implemented, specifically regarding gauge and selector valve markings on Belgian-registered aircraft. The BCAA has since verified and corrected these markings where necessary.
Users of Piper PA-150 aircraft with 180 HP engines are advised to strictly adhere to Aircraft Flight Manual limitations and remain aware of the significant performance and fuel system differences between various aircraft of the same model.